Effects of planting density and nitrogen fertilizer concentration on yield and quality of safflower

To explore the optimum planting density and suitable nitrogen application concecntration of safflower in the irrigation area of the Yellow River diversion, safflower ‘Ganhong No. 1’ was selected as the experimental material and a split-plot experimental design, with the nitrogen treatment as amount area and planting density as subplot, was designed. Under field conditions, three fertilization rates (45, 90, 135 kg·ha⁻¹) and four regimes of planting density (plant-row spacing 30 cm × 60 cm, 25 cm × 60 cm, 25 cm × 50 cm, 27 cm × 40 cm) were applied to study the effects of different nitrogen application rates and planting densities on the yield and quality and nitrogen uptake and utilization of safflower. The results showed that nitrogen application rate and planting density significantly affected the yield, quality and nitrogen utilization of safflower. The agronomic traits, yield traits and nitrogen accumulation increased first and then decreased with the increase of the two. Grain yield, hydroxyl safflower Yellow A (HSYA), nitrogen accumulation, nitrogen apparent efficiency, and nitrogen agronomic efficiency were significantly affected by interaction, and dried flower yield was sensitive to planting density. Among them, HSYA content was the highest under a nitrogen application rate of 90 kg·ha⁻¹ and plant-row spacing of 25 cm × 50 cm, and the other indexes tended to be the highest under a nitrogen application rate of 90 kg·ha⁻¹ and plant-row spacing of 25 cm × 60 cm. Considering the synergic improvement of yield, quality, and nitrogen utilization, the optimal nitrogen application rate was 90 kg·ha⁻¹, and the optimal planting density was 25 cm × 50 cm or 25 cm × 60 cm with row spacing.